[MD Bookmarks] Add toasts.

chrome/browser/resources/md_bookmarks/toast_manager.js

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @fileoverview Element which shows toasts.
+ */
+cr.define('bookmarks', function() {
+
+  var ToastManager = Polymer({
+    is: 'bookmarks-toast-manager',
+
+    properties: {
+      /** @private */
+      showUndo_: Boolean,
+    },
+
+    attached: function() {
+      assert(ToastManager.instance_ == null);
+      ToastManager.instance_ = this;
+    },
+
+    detached: function() {
+      ToastManager.instance_ = null;
+    },
+
+    /**
+     * @param {string} label The label to display inside the toast.
+     * @param {boolean} showUndo Whether the undo button should be shown.
+     */
+    show: function(label, showUndo) {
+      var toast = this.$.toast.get();
+      // TODO(calamity): Support collapsing of long bookmark names in label.
+      this.$$('#content').textContent = label;
+      // We need to hide before showing to ensure that the width of the toast is
+      // recalculated.
+      toast.hide();
+      toast.show();
+
+      this.showUndo_ = showUndo;
+    },
+
+    hide: function() {
+      this.$.toast.get().hide();
+    },
+
+    /** @private */
+    onUndoTap_: function() {
+      // Will hide the toast.
+      this.fire('command-undo');
+    },
+  });
+
+  /** @private {bookmarks.ToastManager} */
+  ToastManager.instance_ = null;
+
+  /** @return {!bookmarks.ToastManager} */
+  ToastManager.getInstance = function() {
+    return assert(ToastManager.instance_);
+  };
+
+  return {
+    ToastManager: ToastManager,
+  };
+});